In this case raft has a meaning of crossing. Not every where there used to be bridges in Latvia, so they used rafts for that. I wouldn’t use word ferry for that in the nowadays meaning just because those were not ferries but really rafts. Term “Boat Raft” means that actually a boat was used to transport whatever to the other coast of river. “Oared Raft” is meant to be raft made of wood like the one from Huckleberry Finn (couldn’t find better comparison for explanation). And the “Roped Raft” means that the raft was moved by pulling the rope in which it was fixed. SO there are no rowing as in the “Oared Raft”